Method for thermally attaching an element to a mounting surface

ABSTRACT

An apparatus for thermally attaching includes a thermally conductive support body (36; 86) with an edge surface (38; 88), a heater cartridge (42), a pneumatically expandable elastomeric element (44-54; 92-102), pinch plates (64, 66; 112, 114) for holding the elastomeric element in place; and passages (60, 62; 108, 110) for pressurizing the heated elastomeric element into contact with an element (24, 26) to be thermally attached to a mounting surface (85).

TECHNICAL FIELD

The invention concerns apparatus and methods for thermally attaching orjoining elements of an article of manufacture. More particularly, theinvention concerns such apparatus and methods which are suited forthermally attaching one element to an inside or outside diameter orother mounting surface of another element or article.

BACKGROUND ART

In various industrial applications, it is necessary to attach or joinone element to another. Aside from typical mechanical fasteners such asclips, screws, rivets and the like, various types of adhesives have beenused, such as contact adhesives and thermally activated adhesives. Forexample, in some types of packages, such as those used for photographicproducts like paper and film, a roll of the product has been providedwith opaque end disks to prevent light from reaching the edges of astrip of paper or film forming the roll. Various types of mechanicalapparatus have been known for thermally attaching the end disks to theinside diameter of a core on which the roll has been wound. Suchmechanical apparatus generally have been rather complex and difficult touse and maintain. Also, mechanical apparatus have tended to leave smallgaps which result in the end disks not being properly attached. In otherapplications, thermal attachments have been made to an outside diameterof an article, using other, similarly complex apparatus. Thus, a needhas existed for a more simple, yet reliable technique for thermallyattaching one element around an inside or outside diameter of anotherelement.

SUMMARY OF THE INVENTION

A primary objective of our invention is to provide a simple, effectiveapparatus and method for thermally attaching an element to a mountingsurface.

Another objective is to provide such an apparatus and method which willensure uniform contact and attachment of the element along the mountingsurface.

Yet another objective is to provide such an apparatus which has fewoperating parts and is easy to service.

These objectives are given only by way of illustrative examples; thusother desirable objectives and advantages inherently achieved by thedisclosed invention may occur or become apparent to those skilled in theart. Nonetheless, the scope of the invention is to be limited only bythe appended claims.

The apparatus of our invention is particularly suited for thermallyattaching along a mounting surface of an article, such as an insidesurface of a core for a roll of web material. The apparatus includes athermally conductive support body having an edge surface; a heaterelement operatively associated with the support body for heating thebody at least at the edge surface; a pneumatically expandableelastomeric element mounted to the support body along the edge surface;and means for directing pressurized gas to the elastomeric element toexpand the elastomeric element away from the edge surface, whereby uponactuation of the heater element, the elastomeric element is heated to atemperature suitable for attaching; and upon introduction of pressurizedgas, the heated elastomeric element expands to permit contact with themounting surface.

The edge surface may be an outside diameter of the support body and theelastomeric element may expand radially outwardly. Alternatively, theedge surface may be an inside diameter of the support body and theelastomeric element may expand radially inwardly. The support body maybe essentially cylindrical and the heater element may be mountedcentrally of the support body. Means may be included for clamping theelastomeric element to the support body. Means may be included forcontrolling movement of the elastomeric element upon introduction ofpressurized gas. When the support body includes an inside or outsidecylindrical surface defining the edge surface; the elastomeric elementmay include a peripheral engagement surface opposite the edge surfaceand a pair of side walls extended radially along the support body, theside walls being compressed against the support body. Each side wall maycomprise a bead; and the support body and the pinch members may havegrooves to engage the beads. The means for directing pressurized gas maycomprise at least one groove in the edge surface; and at least onepassage through the support body to the groove. Means may be providedfor applying vacuum between the elastomeric element and the support bodyto retract the elastomeric element from contact with the mountingsurface into contact with the edge surface of the support body, wherebythe elastomeric member is reheated.

The method of our invention is useful for thermally attaching an elementat a mounting surface of an article and may include steps of providing athermally conductive support body having an edge surface; operativelyassociating a heater element with the support body for heating the bodyat least at the edge surface; mounting a pneumatically expandableelastomeric element to the support body along the edge surface;actuating the heater element to heat the support body and theelastomeric element to a temperature suitable for attaching; positioningan element to be thermally attached at the mounting surface of thearticle; positioning the elastomeric element opposite the element to beattached; and directing pressurized gas to the heated elastomericelement to expand the elastomeric element away from the support bodyinto contact with the element to be attached, whereby the heatedelastomeric element contacts the element to be attached and presses theelement to be attached against the mounting surface of the article tothermally attach the element to the article. When the edge surface is anoutside diameter of the support body, the elastomeric element expandsradially outwardly. When the edge surface is an inside diameter of thesupport body, the elastomeric element expands radially inwardly. Themethod may include applying vacuum between the elastomeric element andthe support body to retract the elastomeric element from contact withthe mounting surface into contact with the edge surface of the supportbody, whereby the elastomeric member is reheated. Alternatively, themethod may include releasing pressure between the elastomeric elementand the support body to retract the elastomeric element from contactwith the mounting surface into contact with the edge surface of thesupport body, whereby the elastomeric member is reheated.

Our invention provides various advantages. Elements such as end disksfor rolls of web material can be attached reliably and uniformly. Theapparatus is simple and easy to maintain. The apparatus can be adaptedto thermally attach elements to a variety of inside or outside surfacesof an article. The elastomeric element conforms rather readily to minorsurface irregularities to help provide good attachment and leaves nogaps along the line of attachment to the mounting surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objectives, features and advantages of theinvention will be apparent from the following more particulardescription of the preferred embodiments of the invention, asillustrated in the accompanying drawings.

FIG. 1 shows an exploded view of a known article of manufacture whichcan be assembled, in part, using the method and apparatus of theinvention.

FIG. 2 shows a centerline sectional elevation view of our apparatuspositioned prior to insertion into the core of a roll of web material tothermally attach an end disk.

FIG. 3 shows a centerline sectional view of our apparatus as insertedinside a core, in its uninflated state.

FIG. 4 shows a centerline sectional view of our apparatus as insertedinside a core, in its inflated state.

FIG. 5 shows a centerline sectional elevation view of our apparatuspositioned after removal from the core of a roll of web material afterthermally attaching an end disk.

FIG. 6 shows a centerline sectional elevation view of an alternativeembodiment of our apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a detailed description of the preferred embodiments ofthe invention, reference being made to the drawings in which the samereference numerals identify the same elements of structure in each ofthe several Figures.

FIG. 1 shows a known article of manufacture which can be assembled usingour invention. A wound roll 10 of light-sensitive web material includesa central, typically flangeless, hollow core 12 having opposite ends anda length approximately equal to the width of a length 14 of such webmaterial. Typically, the bore of core 12 is essentially right circularcylindrical in shape; however, those skilled in the art will appreciatethat our invention also can be used to make thermal attachments toinside mounting surfaces of other shapes. Length 14 is wound onto core12; so that, in the familiar manner, the wound roll 10 has opposite endsurfaces 16, 18. A leading end 20 of length 14 is held in place by astrip of tape 22. A pair of flexible end disks 24, 26 cover end surfaces16, 18. Each disk includes a central portion 28 with a hole 30 somewhatsmaller in diameter than an internal diameter of core 12. The end disksare made from a thin, flexible, opaque material. A plurality of radialcuts 32 extend outwardly from hole 30 through the thickness of the disk,to define a corresponding plurality of tabs which can be folded into thecentral bore of core 12. To facilitate attachment of the tabs within thecore, the tabs, the core or both typically are coated with a thermallyactivated adhesive.

End disks 24, 26 may be made from a material such as a laminationincluding an outer layer of 0.025 mm thick, white, opaque, high densitypolyethylene-low density polyethylene blend extrudate; a second layer of0.076 mm thick linear low density polyethylene film containing carbonblack; and a third layer comprising a coextrusion of 4 pound ethylenevinyl acetate and 16 pound Surlyn extrudate, approximately 0.032 mmthick. In use, the inner layer would face roll 10. Other suitablematerials for end disks 24, 26 include any suitable plastic film orlamination which could include high density polyethylene, polypropylene,Cellophane, Nylon, polyester and various combinations thereof. For usewith light-sensitive web materials, the end disks, of course, must alsobe opaque.

FIG. 2 shows an apparatus 34 according to our invention, positionedopposite a roll 10 on which an end disk has been placed opposite one endsurface. A central, thermally conductive support body 36 is made fromcopper, aluminum or other highly thermally conductive material andincludes a circumferential edge surface 38. Support body 36 and edgesurface 38 have essentially right circular cylindrical geometry in theillustrated embodiment; however, those skilled in the art willappreciate that the geometry may be adjusted as appropriate for amounting surface defined by the interior geometry of core 12. Forexample, a right elliptical cylindrical geometry could be used for someapplications. A central bore 40 receives a cartridge heater 42 having aradially extending mounting flange 43 which bears against an end surfaceof body 36. Heater 42 is mounted centrally in body 36 to ensure that thebody will be warmed essentially uniformly at edge surface 38. For asupport body and pinch plates of the types described in the followingparagraphs, heater cartridge 42 had a length of about 1.5 inch (38.1 mm)and a power rating of 150 watts at 120 volts.

Mounted on body 36 is a pneumatically expandable, elastomeric element 44having a peripheral wall 45 with a peripheral engagement surface 46facing outwardly opposite edge surface 38. As illustrated, elastomericelement 44 rather resembles a tire for a wheel and includes a pair ofradially extended side walls 48, 50 which extend inwardly along supportbody 36. The side walls comprise respective circumferentially andaxially extended attachment beads 52, 54 which extend axially inward andoutward from the side walls. The beads engage respectivecircumferentially extended grooves 56, 58 provided in end surfaces ofsupport body 36. In one actual embodiment, elastomeric element 44 wasmade from a reinforced silicone rubber. Any suitable elastomericmaterial may be used which will withstand the applied pressure andtemperature and will transmit sufficient heat to the end disk or otherelement being attached. Element 44 had an outer diameter of about 2.75inch (69.9 mm), an inside diameter at beads 52, 54 of about 2.3 inch(58.4 mm), an axial length across edge surface of about 0.75 inch (19.1mm), and a wall thickness outboard of the beads of about 0.090 inch(2.29 mm). Other suitable elastomeric materials may be used, such asNeoprene, fluorosilicone rubber, natural rubber, butyl rubber,polyurethane, and the like. Reinforcing fabric or cord also may be used.A circumferentially extended groove 60 is provided in edge surface 38opposite wall 45. Means are provided for directing pressurized gas intoelastomeric element 44. A passage 62 is extended through the supportbody to groove 60, to permit pressurization or evacuation of a volumebetween support body 36 and elastomeric element 44, in a manner to bedescribed subsequently in this specification.

Means are provided for clamping elastomeric element 44 in place onsupport body 36, in the form of a pair of pinch plates or members 64,66. Support body 36 includes a pair of axially extended bosses 68, 70which extend into corresponding bores 69, 71 in the pinch plates. Aplurality of bolts 72 secure the assembly of support body 36,elastomeric element 44, and pinch plates 64, 66 to a support plate 74,shown in dashed lines, of an associated actuator, not illustrated. Tofurther secure elastomeric element 44, the pinch plates include a pairof respective circumferentially extended grooves 76, 78 which alsoengage attachment beads 52, 54. To reduce heat loss from support body36, the pinch plates preferably are molded or machined from a thermallyinsulating material such as Peek (registered trademark of the DuPontCompany), Vespel (registered trademark of the DuPont Company), phenolicplastic, ceramic, and the like. Pinch plate 66 is provided with atapered circumferential surface 79 to facilitate smooth engagement withthe end disk and insertion into core 12. Means are provided forcontrolling movement of the elastomeric element upon pressurization.Pinch plate 64 is provided with a circumferentially and axially extendedengagement land 80 having an axial stop surface 82 for engaging the endedge of core 12 and a radial stop surface 84 for limiting outwardmovement of elastomeric element 44 when inflated.

In use of the apparatus, roll 10 is held with the axis of core 12essentially vertical by any suitable fixture, not illustrated. An enddisk is placed on the end surface of the roll, with opening 30 centeredover the core. Passage 62 is vented to atmosphere or connected to asource of soft vacuum, to allow elastomeric element 44 to move close toedge surface 38. Heater cartridge 42 is actuated to warm support body 36and thereby heat elastomeric element 44 to a temperature suitable forthermally attaching the end disk. For typical thermally activatedadhesives, at least peripheral engagement surface 46 should have atemperature in the range of 250° to 290° F., just before positioning incore 12. Apparatus 34 is then lowered into core 12; so that, taperedsurface 79 folds the tabs surrounding hole 30 into the core, to theposition of FIG. 3. Axial stop surface 82 abuts the end surface of core12. Pressurized air is then directed into passage 62 to causeelastomeric element 44 to expand away from edge surface 38, contact thetaps surrounding hole 30 and press them against a mounting surface 85defined by the inside surface of core 12, as shown in FIG. 4. Radialstop surface 84 prevents over expansion of elastomeric element 44. Dueto the temperature of the elastomeric element, thermally activatedadhesive on the end disk or on surface 85, or both, causes the end disksto be thermally attached to the core. Those skilled in the art willappreciate that our apparatus also could be used to attach an element toa mounting surface without adhesive, if the materials of the element orthe surface become sufficiently sticky when subjected to the heatedelastomeric element. To prevent accumulation of adhesive or dirt on theelastomeric element, a strip of thin polytetrafluoroethylene tape, notillustrated, may be wrapped around the outside of engagement surface 46.After a period of about 1 to 4 seconds, pressure on passage 62 isreleased and apparatus 34 is withdrawn to the position of FIG. 5, readyfor the next cycle of operation. To ensure that the elastomeric elementis promptly reheated to the desired temperature, vacuum may be appliedto passage 62 to drawn peripheral wall 45 into good contact with edgesurface 38.

FIG. 6 illustrates an alternative embodiment of our invention which isuseful to attaching elements to outside peripheral mounting surfaces. Anannular thermally conductive support body 86 has an insidecircumferential edge surface 88. A plurality of symmetrically,circumferentially located radial bores 90, only one being shown, areprovided for a corresponding plurality of heater cartridges 42. Apneumatically expandable elastomeric element 92, which is essentially aninside-out version of elastomeric element 44, includes an insideperipheral engagement surface 94 and a pair of radially outwardlyextended side walls with beads 100, 102. Grooves 104, 106 in supportbody 86 engage the beads. A circumferential groove 108 in edge surface88 is connected with a radial passage 110. A pair of annular pinchplates 112, 114 are provided with circumferential grooves 116, 118 forengaging beads 100, 102. Suitable fasteners, not illustrated, join theassembly. Those skilled in the art will appreciate that in use,elastomeric element 92 expands radially inwardly, thus permittingthermal attachment of elements to essentially cylindrical mountingsurfaces, not illustrated, located inside element 92.

PARTS LIST

10 . . . roll of web of light-sensitive material

12 . . . core with opposite ends and length

14 . . . length of web on core, width equal to length of core

16, 18 . . . opposite end surfaces of roll as-wound

20 . . . leading end of 14

22 . . . strip of tape

24, 26 . . . flexible, opaque end disks

28 . . . central portion of 24, 26

30 . . . central hole in 24, 26

32 . . . radial cuts defining tabs surrounding 30

34 . . . apparatus of invention

36 . . . thermally conductive support body

38 . . . circumferential edge surface of 36

40 . . . central bore

42 . . . heater element or cartridge

43 . . . mounting flange on 42

44 . . . pneumatically expandable elastomeric element

45 . . . peripheral wall of 44

46 . . . peripheral engagement surface

48, 50 . . . side walls

52, 54 . . . beads on 48, 50

56, 58 . . . grooves in 36 to receive 52, 54

60 . . . circumferential groove in 38

62 . . . passage through 36 to 60

64, 66 . . . pinch plates or members

68, 70 . . . axially extended bosses on 36

67, 71 . . . bores in 64, 66

72 . . . bolts

74 . . . support plate of associated actuator

76, 78 . . . grooves in 64, 66 to receive 52, 54

79 . . . tapered circumferential surface on 66

80 . . . circumferential axial engagement land

82 . . . axial stop surface

84 . . . radial stop surface on 80

85 . . . mounting surface on inside of 12

86 . . . annular thermally conductive support body

88 . . . inside circumferential edge surface of 86

90 . . . radial bore for 42

92 . . . pneumatically expandable elastomeric element

94 . . . inside peripheral engagement surface

96, 98 . . . side walls

100, 102 . . . beads on 96,98

104, 106 . . . grooves in 86 to receive 100, 102

108 . . . inside circumferential groove in 94

110 . . . passage

112, 114 . . . annular pinch plates or members

116, 118 . . . grooves in 112, 114 to receive 100, 102

While our invention has been shown and described with reference toparticular embodiments thereof, those skilled in the art will understandthat other variations in form and detail may be made without departingfrom the scope and spirit of our invention.

We claim:
 1. A method for attaching an element to a generallycylindrical mounting surface comprising the steps of:(a) positioning theelement to be attached adjacent to the generally cylindrical mountingsurface, the element to be attached including a temperature activatedbonding means; (b) supporting an annular, elastomeric element on athermally conductive support body, the thermally conductive support bodyincluding a peripheral edge surface; (c) heating the thermallyconductive support body with a cartridge heater while the annular,elastomeric element is in contact with the peripheral edge surfacethereby heating the annular, elastomeric element to a temperaturesufficient to activate the temperature activated bonding means; (d)inflating the annular, elastomeric element with a gas causing theannular, elastomeric element to expand to engage the element to beattached and press the element to be attached against the generallycylindrical mounting surface, the heated, annular, elastomeric elementthereby activating the temperature activated bonding means, the annular,elastomeric element cooling rapidly while inflated and while pressingthe element to be attached against the generally cylindrical mountingsurface.
 2. A method for attaching an element to a mounting surfacecomprising the steps of:(a) positioning the element to be attachedadjacent to the mounting surface, the element to be attached including atemperature activated bonding means; (b) supporting an annular,elastomeric element on a thermally conductive support body, thethermally conductive support body including a peripheral edge surface;(c) heating the thermally conductive support body with a resistanceheater, the thermally conductive support body heating the annular,elastomeric element to a temperature sufficient to activate thetemperature activated bonding means through contact with the peripheraledge of the thermally conductive support body; (d) inflating theannular, elastomeric element with a gas to engage the element to beattached and press the element to be attached against the mountingsurface, the heated, annular, elastomeric element thereby activating thetemperature activated bonding means, the annular elastomeric element nolonger contacting the peripheral edge of the thermally conductivesupport body.
 3. A method as recited in claim 2 wherein:the mountingsurface is generally cylindrical.
 4. A method as recited in claim 3wherein:the annular, elastomeric element is expandable radiallyoutwardly.
 5. A method as recited in claim 3 wherein:the annular,elastomeric element is expandable radially inwardly.
 6. A method asrecited in claim 2 further comprising the step of:deflating the annular,elastomeric element so that the annular, elastomeric element no longerengages the element to be attached.
 7. A method as recited in claim 2further comprising the step of:applying a vacuum to the annular,elastomeric element so that the annular, elastomeric element no longerengages the element to be attached.
 8. A method as recited in claim 2further comprising the step of:allowing the element to be attached tocool below the temperature sufficient to activate the temperatureactivated bonding means while the annular, elastomeric element isinflated and pressing the element to be attached against the mountingsurface.